1. Field of the Invention
This invention relates generally to a disk cartridge in which a recording medium, such as a magnetic disk, an optical disk or the like is accommodated, and more particularly is directed to means for preventing a shutter thereof from being flawed.
2. Description of the Related Art
As shown in FIGS. 12 to 13, disclosed in Japanese Utility Model Registration Publication No. 60-6938 is a disk cartridge, which comprises a cartridge 3 which accommodates a disk-like recording medium 1 therein and has a pair of upper and lower head insertion openings 2, and a shutter 6 which is made of sheet metal, formed substantially into letter U in section by press working, and slidable in a direction of arrows a, b on the outside of the cartridge 3 to open and close the head insertion openings 2 with a pair of covers 4, 5 provided in the shutter 6.
The covers 4, 5 of the shutter 6 have respective openings 7 near to the leading ends thereof at the time of the shutter 6 being moved in the direction of arrow a, and are fitted in respective depressions 8 provided in the upper surface 3a and the lower surface 3b of the cartridge 3. Further, a plurality of projections 9, which are formed by press working so as to be projected vertically upwards from the lower cover 5 of the shutter 6, are slidably fitted into a groove 10, which is provided in the lower surface 3b of the cartridge 3. It is noted that the central plate 1a of the disk-like recording medium 1 is loosely fitted in a turntable insertion opening 11, which is provided substantially at the center of the lower side 3b of the cartridge 3.
When the disk cartridge is out of use, the shutter 6 is moved in the direction of the arrow a toward a closed position indicated in solid lines in FIGS. 12 and 13 by the force of a spring (not shown), which is arranged within the cartridge 3, so that the pair of upper and lower head insertion openings 2 are closed by the pair of covers 4, 5, respectively. Thus, the cartridge 3 is prevented from dust being entered therein through the head insertion openings 2.
When the disk cartridge is inserted into a recording and/or reproducing apparatus, the shutter 6 is slid in the direction of arrow b toward an open position indicated in chain-dotted lines in FIGS. 12 and 13, and as a result the pair of openings 7 of the shutter 6 coincide with the pair of head insertion openings 2. Thus, the head insertion openings are opened. At the same time, a turntable (not shown) of the apparatus is inserted into the cartridge 3 through the turntable insertion opening 11 thereof, and connected with the central plate 1a of the recording medium 1 to be able to drive the recording medium 1. A pair of upper and lower recording or reproducing heads (not shown) are also inserted into the cartridge 3 through the pair of head insertion openings 2 to be able to record information on or reproduce information from the recording medium 1.
The shutter 6 is made of stainless steel of 0.15-0.3 mm in thickness, and in order to give a superior impression upon the disk cartridge, the overall surface of the shutter 6 is generally ornamented with "hair lines" comprising grooves of 100-300 .mu.m in width and 1.5-3 .mu.m in depth. The heights of the hair lines are however very small, so that the hair lines are apt to be collapsed and damaged during manufacture of the shutter 6, because the shutters 6 are rubbed against each other, as shown in FIG. 14, strongly pressed against a conveyor in such duration.
Moreover, to prevent the disk cartridge from lowering its commercial value due to damage to the shutter 6, the shutter 6 must be treated very carefully and inspections of the shutter 6 must be made minutely. Thus, the yield of its manufacture decreases and its production rate becomes bad. In addition, if the shutter 6 is touched directly with bare fingers, the hair lines are soiled with the finger marks or the like and not easily cleaned. Thus, it becomes difficult to give a very good appearance to the disk cartridge.